fix: reload profile watcher in case of unresponsiveness after inactivity

should finally fully resolve https://github.com/ilya-zlobintsev/LACT/issues/448

lact-daemon/src/server/profiles.rs

@@ -6,6 +6,7 @@ use copes::solver::PEvent;
 use futures::StreamExt;
 use lact_schema::{ProfileRule, ProfileWatcherState};
 use std::{
+    process::Command,
     rc::Rc,
     time::{Duration, Instant},
 };
@@ -14,13 +15,14 @@ use tokio::{
     sync::{mpsc, Mutex, Notify},
     time::sleep,
 };
-use tracing::{debug, error, info, trace};
+use tracing::{debug, error, info, trace, warn};
 use zbus::AsyncDrop;
 
 static PROFILE_WATCHER_LOCK: Mutex<()> = Mutex::const_new(());
 
 const PROFILE_WATCHER_MIN_DELAY_MS: u64 = 50;
 const PROFILE_WATCHER_MAX_DELAY_MS: u64 = 500;
+const SUSPICIOUS_INACTIVITY_PERIOD_SECS: u64 = 30;
 
 #[derive(Debug)]
 enum ProfileWatcherEvent {
@@ -120,6 +122,12 @@ pub async fn run_watcher(handler: Handler, mut command_rx: mpsc::Receiver<Profil
 
     update_profile(&handler).await;
 
+    let mut should_reload = false;
+    let mut suspiciously_quiet = false;
+
+    let inactivity_timer = sleep(Duration::from_secs(SUSPICIOUS_INACTIVITY_PERIOD_SECS));
+    tokio::pin!(inactivity_timer);
+
     loop {
         select! {
             Some(cmd) = command_rx.recv() => {
@@ -131,7 +139,10 @@ pub async fn run_watcher(handler: Handler, mut command_rx: mpsc::Receiver<Profil
                 }
             }
             Some(event) = event_rx.recv() => {
-                handle_profile_event(&event, &handler).await;
+                suspiciously_quiet = false;
+                inactivity_timer.as_mut().reset(tokio::time::Instant::now() + Duration::from_secs(SUSPICIOUS_INACTIVITY_PERIOD_SECS));
+
+                handle_profile_event(&event, &handler, &mut should_reload);
 
                 // It is very common during system usage that multiple processes start at the same time, or there are processes
                 // that start and exit right away.
@@ -160,13 +171,38 @@ pub async fn run_watcher(handler: Handler, mut command_rx: mpsc::Receiver<Profil
                         Some(event) = event_rx.recv() => {
                             trace!("got another process event, delaying profile update");
                             min_timeout.as_mut().reset(tokio::time::Instant::now() + Duration::from_millis(PROFILE_WATCHER_MIN_DELAY_MS));
-                            handle_profile_event(&event, &handler).await;
+                            handle_profile_event(&event, &handler, &mut should_reload);
                         }
                     }
                 }
 
                 update_profile(&handler).await;
             },
+            () = &mut inactivity_timer => {
+                if suspiciously_quiet {
+                    error!("no profile watcher events detected even after manual invocation, restarting watcher");
+                    should_reload = true;
+                } else {
+                    debug!("no event activity detected in {SUSPICIOUS_INACTIVITY_PERIOD_SECS} seconds, checking listener liveness by spawning a process");
+                    let next_check_delta = match Command::new("uname").output() {
+                        Ok(_) => {
+                            suspiciously_quiet = true;
+                            // The event regarding the just spawned command should be received within this time period
+                            Duration::from_secs(SUSPICIOUS_INACTIVITY_PERIOD_SECS / 3)
+                        }
+                        Err(err) => {
+                            warn!("could not spawn test command: {err}");
+                            Duration::from_secs(SUSPICIOUS_INACTIVITY_PERIOD_SECS)
+                        }
+                    };
+                    inactivity_timer.as_mut().reset(tokio::time::Instant::now() + next_check_delta);
+                }
+            }
+        }
+
+        if should_reload {
+            handler.start_profile_watcher().await;
+            break;
         }
     }
 
@@ -178,8 +214,7 @@ pub async fn run_watcher(handler: Handler, mut command_rx: mpsc::Receiver<Profil
     }
 }
 
-async fn handle_profile_event(event: &ProfileWatcherEvent, handler: &Handler) {
+fn handle_profile_event(event: &ProfileWatcherEvent, handler: &Handler, should_reload: &mut bool) {
-    let mut should_reload = false;
     {
         let mut state_guard = handler.profile_watcher_state.borrow_mut();
         let Some(state) = state_guard.as_mut() else {
@@ -192,7 +227,7 @@ async fn handle_profile_event(event: &ProfileWatcherEvent, handler: &Handler) {
                     trace!("process {pid} ({}) started", info.name);
                     if info.name.as_ref() == gamemode::PROCESS_NAME {
                         info!("detected gamemode daemon, reloading profile watcher");
-                        should_reload = true;
+                        *should_reload = true;
                     }
                     state.push_process(*pid.as_ref(), info);
                 }
@@ -201,8 +236,11 @@ async fn handle_profile_event(event: &ProfileWatcherEvent, handler: &Handler) {
                 }
             },
             ProfileWatcherEvent::Process(PEvent::Exit(pid)) => {
+                if let Some(info) = state.remove_process(*pid.as_ref()) {
+                    trace!("process {pid} ({}) exited", info.name);
+                } else {
                     trace!("process {pid} exited");
-                state.remove_process(*pid.as_ref());
+                }
             }
             ProfileWatcherEvent::Gamemode(PEvent::Exec(pid)) => {
                 state.gamemode_games.insert(*pid.as_ref());
@@ -212,10 +250,6 @@ async fn handle_profile_event(event: &ProfileWatcherEvent, handler: &Handler) {
             }
         }
     }
-
-    if should_reload {
-        handler.start_profile_watcher().await;
-    }
 }
 
 async fn update_profile(handler: &Handler) {

lact-daemon/src/server/system.rs

@@ -13,7 +13,7 @@ use std::{
     sync::atomic::{AtomicBool, Ordering},
 };
 use tokio::{process::Command, sync::Notify};
-use tracing::{error, info, warn};
+use tracing::{debug, error, info, warn};
 
 static OC_TOGGLED: AtomicBool = AtomicBool::new(false);
 
@@ -226,6 +226,11 @@ pub(crate) fn listen_netlink_kernel_event(notify: &Notify) -> anyhow::Result<()>
         for raw_line in buf.split(|c| *c == b'\0') {
             match std::str::from_utf8(raw_line) {
                 Ok(line) => {
+                    if line.is_empty() {
+                        continue;
+                    }
+
+                    debug!("kernel event line: '{line}'");
                     if let Some(subsystem) = line.strip_prefix("SUBSYSTEM=") {
                         if subsystem == "drm" {
                             notify.notify_one();

lact-schema/src/profiles.rs

@@ -29,14 +29,17 @@ impl ProfileWatcherState {
         self.process_names_map.entry(name).or_default().insert(pid);
     }
 
-    pub fn remove_process(&mut self, pid: i32) {
+    pub fn remove_process(&mut self, pid: i32) -> Option<ProcessInfo> {
-        if let Some(info) = self.process_list.shift_remove(&pid) {
+        if let Some(mut info) = self.process_list.shift_remove(&pid) {
             if let Entry::Occupied(mut entry) = self.process_names_map.entry(info.name) {
                 entry.get_mut().remove(&pid);
                 if entry.get().is_empty() {
-                    entry.remove();
+                    let (key, _) = entry.remove_entry();
+                    info.name = key;
+                    return Some(info);
                 }
             }
         }
+        None
     }
 }